Enhanced Electrochemical Sensing of Dopamine and Uric Acid Using a Sol-Gel Fabricated MWCNT Array-Modified Carbon Electrode

In this study, a glassy carbon electrode (GCE) modified with a vertically aligned array of multiwalled carbon nanotubes (MWCNTs) was fabricated via a temperature-controlled sol-gel method. The vertically aligned MWCNT structure significantly enhances the electrode’s surface modification efficiency, offering superior electrochemical performance compared to conventional methods. The resulting MWCNT array-modified GCE demonstrates excellent selectivity by clearly differentiating the anodic oxidation potentials of dopamine (DA) and uric acid (UA), even in complex biological matrices. To further improve the electroactive properties, the modified electrode was pre-treated with ethanol and acetone prior to electrochemical measurements. Remarkably, this pre-treatment enabled the detection of an additional two-electron oxidation process during dopamine oxidation, associated with the conversion of 5,6-dihydroxyindole to indole-5,6-quinone—a feature not typically observed in other CNT-based electrodes. The optimized sensor exhibited high sensitivity and selectivity for the simultaneous detection of DA and UA in human serum and urine samples, achieving recovery rates ranging from 95% to 110%. These results highlight the potential of the sol-gel fabricated MWCNT array-GCE as an efficient and reliable platform for advanced biosensing applications.